A valve timing controller controls opening and closing timing of an intake valve or an exhaust valve in an internal combustion engine by changing a rotation phase between a crankshaft and a camshaft. The valve timing controller has a housing rotating with the crankshaft, and a vane rotor rotating with the camshaft. The valve timing controller controls the valve timing by supplying working oil to an advance chamber or a retard chamber defined in the housing, so as to rotate the vane rotor. JP-2003-314229A (US 2003/0196627) describes a check valve system in which a reed valve is disposed in an oil passage which supplies the working oil to the advance chamber and the retard chamber as a check valve.
If a cross-sectional area of the oil passage connected to the reed valve is made smaller, the valve opening speed of the reed valve is made faster. However, in this case, a large pressure loss is generated when a large amount of the working oil is made to flow the oil passage, so the responsivity becomes worse because the relative rotation speed of the vane rotor cannot be raised.
In contrast, if the cross-sectional area of the oil passage is made larger, the valve opening speed of the reed valve becomes slow when a small amount of the working oil is made to flow the oil passage. In this case, the reed valve cannot work as the check valve and the responsivity becomes worse.